1. Redox-Responsive H-Bonding: Amplifying the Effect of Electron Transfer Using Proton-Coupled Electron Transfer
- Author
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Sean T. Toenjes, Kiyeol Baek, Jeffrey L. Gustafson, Diane K. Smith, and Hyejeong Choi
- Subjects
Proton ,Hydrogen bond ,Chemistry ,Ionic bonding ,General Chemistry ,010402 general chemistry ,Redox responsive ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Electron transfer ,Crystallography ,Colloid and Surface Chemistry ,Nmr titration ,Proton-coupled electron transfer ,Cyclic voltammetry - Abstract
A new strategy to create highly redox-responsive H-bond dimers based on proton-coupled electron transfer is proposed that capitalizes on the importance of secondary H-bonds in determining overall binding strength in H-bond dimers. Electron transfer induced proton transfer across a H-bond can be used to significantly strengthen the overall binding by both creating strong ionic H-bonds and changing the secondary H-bonds from unfavorable to favorable. The viability and potency of this approach are demonstrated with an electroactive DAD (A = H-acceptor, D = H-donor) array, H(MQ+)H, paired with an electroinactive ADA array, O(NH)O. NMR titration of H(MQ+)H with O(NH)O in 0.1 M NBu4PF6/CD2Cl2 gives a Kassoc of 500 M-1, typical of DAD-ADA dimers. However, upon two-electron reduction in 0.1 M NBu4PF6/CH2Cl2, cyclic voltammetry studies indicate a 1.8 × 105 increase in binding strength, corresponding to a very large Kassoc of 9 × 107 M-1. The latter value is typical of DDD-AAA H-bond dimers, consistent with proton transfer across the central H-bond upon reduction. more...
- Published
- 2020
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